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Subject[PATCH v4 6/7] tracing: Add enable_hist/disable_hist triggers
Date
Similar to enable_event/disable_event triggers, these triggers enable
and disable the aggregation of events into maps rather than enabling
and disabling their writing into the trace buffer.

They can be used to automatically start and stop hist triggers based
on a matching filter condition.

If there's a paused hist trigger on system:event, the following would
start it when the filter condition was hit:

# echo enable_hist:system:event [ if filter] > event/trigger

And the following would disable a running system:event hist trigger:

# echo disable_hist:system:event [ if filter] > event/trigger

See Documentation/trace/events.txt for real examples.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
---
include/linux/ftrace_event.h | 1 +
kernel/trace/trace.c | 11 ++++
kernel/trace/trace.h | 32 ++++++++++
kernel/trace/trace_events_hist.c | 115 ++++++++++++++++++++++++++++++++++++
kernel/trace/trace_events_trigger.c | 71 ++++++++++++----------
5 files changed, 199 insertions(+), 31 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index d1fa0b5..0664b42 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -417,6 +417,7 @@ enum event_trigger_type {
ETT_STACKTRACE = (1 << 2),
ETT_EVENT_ENABLE = (1 << 3),
ETT_EVENT_HIST = (1 << 4),
+ ETT_HIST_ENABLE = (1 << 5),
};

extern int filter_match_preds(struct event_filter *filter, void *rec);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a08f904..31ed112 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3724,6 +3724,10 @@ static const char readme_msg[] =
"\t trigger: traceon, traceoff\n"
"\t enable_event:<system>:<event>\n"
"\t disable_event:<system>:<event>\n"
+#ifdef CONFIG_HIST_TRIGGERS
+ "\t enable_hist:<system>:<event>\n"
+ "\t disable_hist:<system>:<event>\n"
+#endif
#ifdef CONFIG_STACKTRACE
"\t\t stacktrace\n"
#endif
@@ -3787,6 +3791,13 @@ static const char readme_msg[] =
"\t restart a paused hist trigger.\n\n"
"\t The 'clear' param will clear the contents of a running hist\n"
"\t trigger and leave its current paused/active state.\n\n"
+ "\t The enable_hist and disable_hist triggers can be used to\n"
+ "\t have one event conditionally start and stop another event's\n"
+ "\t already-attached hist trigger. Any number of enable_hist\n"
+ "\t and disable_hist triggers can be attached to a given event,\n"
+ "\t allowing that event to kick off and stop aggregations on\n"
+ "\t a host of other events. See Documentation/trace/events.txt\n"
+ "\t for examples.\n"
#endif
;

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 1ae4d90..d95264c 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1102,8 +1102,10 @@ extern const struct file_operations event_hist_fops;

#ifdef CONFIG_HIST_TRIGGERS
extern int register_trigger_hist_cmd(void);
+extern int register_trigger_hist_enable_disable_cmds(void);
#else
static inline int register_trigger_hist_cmd(void) { return 0; }
+static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
#endif

extern int register_trigger_cmds(void);
@@ -1121,6 +1123,34 @@ struct event_trigger_data {
struct list_head list;
};

+/* Avoid typos */
+#define ENABLE_EVENT_STR "enable_event"
+#define DISABLE_EVENT_STR "disable_event"
+#define ENABLE_HIST_STR "enable_hist"
+#define DISABLE_HIST_STR "disable_hist"
+
+struct enable_trigger_data {
+ struct ftrace_event_file *file;
+ bool enable;
+ bool hist;
+};
+
+extern int event_enable_trigger_print(struct seq_file *m,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *data);
+extern void event_enable_trigger_free(struct event_trigger_ops *ops,
+ struct event_trigger_data *data);
+extern int event_enable_trigger_func(struct event_command *cmd_ops,
+ struct ftrace_event_file *file,
+ char *glob, char *cmd, char *param);
+extern int event_enable_register_trigger(char *glob,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *data,
+ struct ftrace_event_file *file);
+extern void event_enable_unregister_trigger(char *glob,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *test,
+ struct ftrace_event_file *file);
extern void trigger_data_free(struct event_trigger_data *data);
extern int event_trigger_init(struct event_trigger_ops *ops,
struct event_trigger_data *data);
@@ -1134,6 +1164,8 @@ extern int set_trigger_filter(char *filter_str,
struct event_trigger_data *trigger_data,
struct ftrace_event_file *file);
extern int register_event_command(struct event_command *cmd);
+extern int unregister_event_command(struct event_command *cmd);
+extern int register_trigger_hist_enable_disable_cmds(void);

/**
* struct event_trigger_ops - callbacks for trace event triggers
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 6fe3400..200f0ad 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1591,3 +1591,118 @@ __init int register_trigger_hist_cmd(void)

return ret;
}
+
+static void
+hist_enable_trigger(struct event_trigger_data *data, void *rec)
+{
+ struct enable_trigger_data *enable_data = data->private_data;
+ struct event_trigger_data *test;
+
+ list_for_each_entry_rcu(test, &enable_data->file->triggers, list) {
+ if (test->cmd_ops->trigger_type == ETT_EVENT_HIST) {
+ if (enable_data->enable)
+ test->paused = false;
+ else
+ test->paused = true;
+ break;
+ }
+ }
+}
+
+static void
+hist_enable_count_trigger(struct event_trigger_data *data, void *rec)
+{
+ if (!data->count)
+ return;
+
+ if (data->count != -1)
+ (data->count)--;
+
+ hist_enable_trigger(data, rec);
+}
+
+static struct event_trigger_ops hist_enable_trigger_ops = {
+ .func = hist_enable_trigger,
+ .print = event_enable_trigger_print,
+ .init = event_trigger_init,
+ .free = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_enable_count_trigger_ops = {
+ .func = hist_enable_count_trigger,
+ .print = event_enable_trigger_print,
+ .init = event_trigger_init,
+ .free = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_disable_trigger_ops = {
+ .func = hist_enable_trigger,
+ .print = event_enable_trigger_print,
+ .init = event_trigger_init,
+ .free = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops hist_disable_count_trigger_ops = {
+ .func = hist_enable_count_trigger,
+ .print = event_enable_trigger_print,
+ .init = event_trigger_init,
+ .free = event_enable_trigger_free,
+};
+
+static struct event_trigger_ops *
+hist_enable_get_trigger_ops(char *cmd, char *param)
+{
+ struct event_trigger_ops *ops;
+ bool enable;
+
+ enable = (strcmp(cmd, ENABLE_HIST_STR) == 0);
+
+ if (enable)
+ ops = param ? &hist_enable_count_trigger_ops :
+ &hist_enable_trigger_ops;
+ else
+ ops = param ? &hist_disable_count_trigger_ops :
+ &hist_disable_trigger_ops;
+
+ return ops;
+}
+
+static struct event_command trigger_hist_enable_cmd = {
+ .name = ENABLE_HIST_STR,
+ .trigger_type = ETT_HIST_ENABLE,
+ .func = event_enable_trigger_func,
+ .reg = event_enable_register_trigger,
+ .unreg = event_enable_unregister_trigger,
+ .get_trigger_ops = hist_enable_get_trigger_ops,
+ .set_filter = set_trigger_filter,
+};
+
+static struct event_command trigger_hist_disable_cmd = {
+ .name = DISABLE_HIST_STR,
+ .trigger_type = ETT_HIST_ENABLE,
+ .func = event_enable_trigger_func,
+ .reg = event_enable_register_trigger,
+ .unreg = event_enable_unregister_trigger,
+ .get_trigger_ops = hist_enable_get_trigger_ops,
+ .set_filter = set_trigger_filter,
+};
+
+static __init void unregister_trigger_hist_enable_disable_cmds(void)
+{
+ unregister_event_command(&trigger_hist_enable_cmd);
+ unregister_event_command(&trigger_hist_disable_cmd);
+}
+
+__init int register_trigger_hist_enable_disable_cmds(void)
+{
+ int ret;
+
+ ret = register_event_command(&trigger_hist_enable_cmd);
+ if (WARN_ON(ret < 0))
+ return ret;
+ ret = register_event_command(&trigger_hist_disable_cmd);
+ if (WARN_ON(ret < 0))
+ unregister_trigger_hist_enable_disable_cmds();
+
+ return ret;
+}
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index a09eba3..7105f15 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -338,7 +338,7 @@ __init int register_event_command(struct event_command *cmd)
* Currently we only unregister event commands from __init, so mark
* this __init too.
*/
-static __init int unregister_event_command(struct event_command *cmd)
+__init int unregister_event_command(struct event_command *cmd)
{
struct event_command *p, *n;
int ret = -ENODEV;
@@ -1051,15 +1051,6 @@ static __init void unregister_trigger_traceon_traceoff_cmds(void)
unregister_event_command(&trigger_traceoff_cmd);
}

-/* Avoid typos */
-#define ENABLE_EVENT_STR "enable_event"
-#define DISABLE_EVENT_STR "disable_event"
-
-struct enable_trigger_data {
- struct ftrace_event_file *file;
- bool enable;
-};
-
static void
event_enable_trigger(struct event_trigger_data *data, void *rec)
{
@@ -1089,14 +1080,16 @@ event_enable_count_trigger(struct event_trigger_data *data, void *rec)
event_enable_trigger(data, rec);
}

-static int
-event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
- struct event_trigger_data *data)
+int event_enable_trigger_print(struct seq_file *m,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;

seq_printf(m, "%s:%s:%s",
- enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR,
+ enable_data->hist ?
+ (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
+ (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
enable_data->file->event_call->class->system,
ftrace_event_name(enable_data->file->event_call));

@@ -1113,9 +1106,8 @@ event_enable_trigger_print(struct seq_file *m, struct event_trigger_ops *ops,
return 0;
}

-static void
-event_enable_trigger_free(struct event_trigger_ops *ops,
- struct event_trigger_data *data)
+void event_enable_trigger_free(struct event_trigger_ops *ops,
+ struct event_trigger_data *data)
{
struct enable_trigger_data *enable_data = data->private_data;

@@ -1160,10 +1152,9 @@ static struct event_trigger_ops event_disable_count_trigger_ops = {
.free = event_enable_trigger_free,
};

-static int
-event_enable_trigger_func(struct event_command *cmd_ops,
- struct ftrace_event_file *file,
- char *glob, char *cmd, char *param)
+int event_enable_trigger_func(struct event_command *cmd_ops,
+ struct ftrace_event_file *file,
+ char *glob, char *cmd, char *param)
{
struct ftrace_event_file *event_enable_file;
struct enable_trigger_data *enable_data;
@@ -1172,6 +1163,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
struct trace_array *tr = file->tr;
const char *system;
const char *event;
+ bool hist = false;
char *trigger;
char *number;
bool enable;
@@ -1196,8 +1188,15 @@ event_enable_trigger_func(struct event_command *cmd_ops,
if (!event_enable_file)
goto out;

- enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#ifdef CONFIG_HIST_TRIGGERS
+ hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
+ (strcmp(cmd, DISABLE_HIST_STR) == 0));

+ enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+ (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
+ enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#endif
trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);

ret = -ENOMEM;
@@ -1217,6 +1216,7 @@ event_enable_trigger_func(struct event_command *cmd_ops,
INIT_LIST_HEAD(&trigger_data->list);
RCU_INIT_POINTER(trigger_data->filter, NULL);

+ enable_data->hist = hist;
enable_data->enable = enable;
enable_data->file = event_enable_file;
trigger_data->private_data = enable_data;
@@ -1294,10 +1294,10 @@ event_enable_trigger_func(struct event_command *cmd_ops,
goto out;
}

-static int event_enable_register_trigger(char *glob,
- struct event_trigger_ops *ops,
- struct event_trigger_data *data,
- struct ftrace_event_file *file)
+int event_enable_register_trigger(char *glob,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *data,
+ struct ftrace_event_file *file)
{
struct enable_trigger_data *enable_data = data->private_data;
struct enable_trigger_data *test_enable_data;
@@ -1307,6 +1307,8 @@ static int event_enable_register_trigger(char *glob,
list_for_each_entry_rcu(test, &file->triggers, list) {
test_enable_data = test->private_data;
if (test_enable_data &&
+ (test->cmd_ops->trigger_type ==
+ data->cmd_ops->trigger_type) &&
(test_enable_data->file == enable_data->file)) {
ret = -EEXIST;
goto out;
@@ -1331,10 +1333,10 @@ out:
return ret;
}

-static void event_enable_unregister_trigger(char *glob,
- struct event_trigger_ops *ops,
- struct event_trigger_data *test,
- struct ftrace_event_file *file)
+void event_enable_unregister_trigger(char *glob,
+ struct event_trigger_ops *ops,
+ struct event_trigger_data *test,
+ struct ftrace_event_file *file)
{
struct enable_trigger_data *test_enable_data = test->private_data;
struct enable_trigger_data *enable_data;
@@ -1344,6 +1346,8 @@ static void event_enable_unregister_trigger(char *glob,
list_for_each_entry_rcu(data, &file->triggers, list) {
enable_data = data->private_data;
if (enable_data &&
+ (data->cmd_ops->trigger_type ==
+ test->cmd_ops->trigger_type) &&
(enable_data->file == test_enable_data->file)) {
unregistered = true;
list_del_rcu(&data->list);
@@ -1363,8 +1367,12 @@ event_enable_get_trigger_ops(char *cmd, char *param)
struct event_trigger_ops *ops;
bool enable;

+#ifdef CONFIG_HIST_TRIGGERS
+ enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+ (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
-
+#endif
if (enable)
ops = param ? &event_enable_count_trigger_ops :
&event_enable_trigger_ops;
@@ -1435,6 +1443,7 @@ __init int register_trigger_cmds(void)
register_trigger_snapshot_cmd();
register_trigger_stacktrace_cmd();
register_trigger_enable_disable_cmds();
+ register_trigger_hist_enable_disable_cmds();
register_trigger_hist_cmd();

return 0;
--
1.9.3


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